Outer space is big. Really, really, really big. And that’s why NASA has no plans at present to send a spacecraft to any of the 2,000 and more known planets beyond our solar system. Meanwhile, NASA isn’t the only game in town anymore, and another organization has announced an investment in proof-of-concept studies for a plan to reach Alpha Centauri within 20 years. Alpha Centauri is the nearest star system to our sun at 4.3 light-years away. That’s about 25 trillion miles (40 trillion km) away from Earth – nearly 300,000 times the distance from the Earth to the sun. How might we travel to Alpha Centauri, the next-nearest star? And how long would it take to get there? Follow the links below to learn more.
Why won’t a conventional rocket work? Consider the Space Shuttles, which traveled only a few hundred kilometers into space. If Earth were the size of a sand grain, this would be about the width of a hair in contrast to a 10-kilometer distance to Alpha Centauri. You’d need about 10,000 shuttle main engines in sequence just to build up a decent speed (say, 1/100th light speed).
The Space Shuttles weren’t starships. At a maximum speed of about 17,600 mph (about 28,300 kph), it would have taken a Space Shuttle about 165,000 years to reach Alpha Centauri.
How about the Voyager spacecraft? These two unmanned space probes – Voyager 1 and Voyager 2 – were launched in 1977. They’re now heading out of our solar system. The Voyagers aren’t aimed toward Alpha Centauri, but if they were, they’d take tens of thousands of years to get there. Eventually, the Voyagers will pass other stars. In about 40,000 years, Voyager 1 will drift within 1.6 light-years (9.3 trillion miles) of AC+79 3888, a star in the constellation of Camelopardalis. In some 296,000 years, Voyager 2 will pass 4.3 light-years from Sirius, the brightest star in the sky. Hmm, 4.3 light-years. That’s the distance between us and Alpha Centauri.
What about the New Horizons spacecraft, the first spacecraft ever to visit Pluto and its moons. NASA’s New Horizons spacecraft travels at 36,373 miles per hour (58,536 km/h). Launched from Earth in mid-January, 2006, it reached Pluto in mid-July, 2015 … nine-and-a-half years later. If New Horizons were aimed toward the Alpha Centauri system, which it isn’t, it would take this spacecraft about 78,000 years to get there.
Warp drive? So conventional rockets would take tens to hundreds of thousands of years to travel to Alpha Centauri. But what if we could travel faster than light? Sound impossible? A couple of years ago, Dr. Harold “Sonny” White – who leads NASA’s Advanced Propulsion Team at Johnson Space Center – claimed to have made a discovery which made plausible the idea of faster-than-light travel, via a concept known as the Alcubierre warp drive.
This concept is based on ideas put forward by Mexican physicist Miguel Alcubierre in 1994. He suggested that faster-than-light travel might be achieved by distorting spacetime, as shown in the illustration above.
Harold “Sonny” White has been working to investigate these ideas further, and, in June of 2014, he unveiled images of what a faster-than-light ship might look like. Artist Mark Rademaker based these designs on White’s theoretical ideas. He said creating them took more than 1,600 hours, and they are very cool. See the 2014 faster-than-light spacecraft designs on this Flickr page.
The video below presents Harold White’s talk at the SpaceVision 2013 Space Conference in November, 2013 in Phoenix. He talks about the concepts and progress in warp-drive development over recent decades.
Is it faster-than-light travel possible, via the Alcubierre warp drive? As with conventional propulsion systems, the problem is energy. In this case, it’s the type of energy the warp drive would need. Daily Kos reported:
In order to form the warp field/bubble, a region of space-time with negative energy density (i.e. repulsing space-time) is necessary. Scientific models predict exotic matter with a negative energy may exist, but it has never been observed. All forms of matter and light have a positive energy density, and create an attractive gravitational field.
So faster-than-light travel via the Alcubierre warp drive is highly speculative, to say the least.
With current technologies, it’s not possible.
However, if it could be accomplished, it would reduce the travel time to Alpha Centauri from thousands of years to just days.
Breakthrough Starshot. In April, 2016, the Breakthrough Initiatives – led by Russian billionaire Yuri Milner – announced a $100 million investment in proof-of concept studies for an all-new way to get to the stars.
Well, not all new, exactly. The Breakthrough Starshot project relies on technologies that are being tested now, and also on some new technologies that have been around only a few years. But it does put these technologies together in a way that’s entirely new, and extremely visionary.
They Breakthrough Starshot team has some heavy hitters, including physicist Stephen Hawking and Facebook’s Mark Zuckerberg. It proposes to use the $100 million to learn whether it’s possible to use a 100-gigawatt light beam and light sails to propel some 1,000 ultra-lightweight nanocraft to 20 percent of light speed. If it’s shown to be possible, such a mission could (hypothetically) reach Alpha Centauri within about 20 years of its launch.
There are a lot of appealing things about this project. Although the idea for the nanostarships is extremely innovative, for example, the use of light sails is currently in the process of being tested by another organization, the Planetary Society, with a publicly funded project called LightSail. The first LightSail orbital test, in 2015, tested the spacecraft’s solar sail deployment mechanism, but did not fly high enough for the push from solar sailing to overcome Earth’s atmospheric drag.
The second LightSail test mission is planned for 2016. Read more about the Planetary Society’s LightSail.
There’s so much to say about Breakthrough Starshot that I’ve written another article about it, which you can find here.
Let me just add here that the concept is exciting, and I’m as anxious as you are to follow it in the years ahead!
Bottom line: At 4.3 light-years away, the Alpha Centauri system is the nearest star system to our Earth and sun, but getting there would be extremely difficult.
Deborah Byrd created the EarthSky radio series in 1991 and EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.